1. Field of the Invention
The present invention relates to a presentation device which is advantageous for giving presentations in which a presenter explains the content of materials such as manuscripts and photographs to an audience while the materials are displayed on a display device such as a screen or a monitor.
2. Description of the Related Art
Lectures, explanations of goods, educational presentations, etc., are given while images of materials are displayed on a screen. These kinds of performances are called “presentations” hereinafter. In these presentations, a presenter indicates specific parts on images of materials projected on the screen by performing a pointing operation. Laser pointers emitting laser beams have generally been used in pointing operation methods. However, the laser beams are dangerous.
Therefore, the Applicant of the present invention previously proposed a presentation system in which a virtual screen is generated near a presenter, a camera photographs the state in which the presenter virtually performs a pointing operation on the virtual screen using an indication mark, and a point image is displayed at the position on an image projected on the screen, which corresponds to the position of the indication mark on image data, as described in Japanese Unexamined Patent Application Publication No. 2003-108305. In this proposal, there is no danger from the laser beams, it is possible to suppress shaking by image processing, and it is possible to vary the shape of the point image. In Japanese Unexamined Patent Application Publication No. 2002-17184 proposed by the Applicant, not only the presenter, but also, members of the audience may perform a pointing operation by using a virtual screen.
On a virtual screen, a presenter virtually performs a pointing operation by using the indication mark in the above manner, and XY coordinates are generated. The indication mark is composed of light emitted by a light pen. When an arbitrary position on the virtual screen is indicated by the indication mark, the position of the indication mark on the XY coordinates is calculated based on image data obtained by a camera photographing the indication mark, and a point image is displayed at a position on the screen, which corresponds to the calculated position. The method of generating the virtual screen is as follows. For example, a camera photographs the state in which light is emitted at two diagonal points. A rectangular virtual screen area having a diagonal line connecting two diagonal points to each other is zoomed in the camera angle of view. XY coordinates are generated on the virtual screen area, whereby the virtual screen area is set as a virtual screen.
In the above method of generating the virtual screen, the position of the presenter is not restricted, and it is also possible for members of the audience to perform a pointing operation, whereby the presentation can be made more flexible and other effects can be obtained. The size of the virtual screen is made to fit the size of the presenter or the audience. However, this method of generating the virtual screen is troublesome. Due to this, it is necessary to teach the audience the method in order for the audience to perform pointing operations. As a result, the presentation may not be performed smoothly. To overcome this disadvantage, it is thought that the virtual screen should be set so as to be fixed before the presentation. In this case, however, the size of the virtual screen cannot be changed, and it is troublesome to set the position of the fixed virtual screen, and it is thereby difficult for the presenter to use a fixed virtual screen.